1. Field of the Invention
This particular invention, in general, pertains to a thrust collar apparatus for use in conjunction with tube expanding tools of the roller and mandrel type which primarily function to expand tubes situated within corresponding openings formed in a tube sheet or other like structure. In particular, the present invention is related to a novel and improved reversible thrust collar apparatus which, in association with a tube expander apparatus, easily facilitates, in a simple and reliable fashion, the expansion of tubes having ends flush with or projecting from a tube sheet.
2. Description of the Prior Art
Typically, rotary expanding tool assemblies of the roller and mandrel type are characterized as including a cage member having an externally threaded portion, and a plurality of discrete circumferentially spaced and longitudinally extending slots which are skewed. The slots carry a plurality of conventional tapered expanding rollers. Also, the cage member of the above assembly rotatably surrounds a tapered rotatable mandrel passing therethrough which contacts the rollers. In operation, the mandrel is rotatably driven, in any suitable manner, after the tube expanding assembly with mandrel and cage have been inserted into the tube. Ordinarily during rotation of the mandrel, it is advanced so as to force the expanding rollers radially outwardly into contact with the tube. Since the rollers make contact with the inner surface of the tube, rotation of the mandrel results in the cage member being correspondingly rotated. By virtue of the expanding rollers being skewed with respect to the axes of the mandrel and cage, the cage is drawn into the tube until stopped by a stop collar member connected to and rotatable with the cage member which abuttingly engages either the end of the particular tube being expanded or the associated tube sheet. In situations wherein the stop collar initially contacts the tube sheet, the further rotation of the cage tends to pull the tube outwardly. This linear movement is arrested whenever the end of the tube abuts the stop collar. The stop collar ordinarily functions to, among other things, control positioning of the tube end relative to the tube sheet and hold the tube which is to be expanded from rotation.
As a consequence of the foregoing, the expanded tube is securely fastened within the sheet and may form, for example, a fluid-tight joint which protects against leakage. Customarily, such kinds of tube expanders would be in conjunction with tubes for use in heat exchangers, condensers, and the like.
One of the difficulties frequently encountered in expanding such tubes in tube sheets or the like arises by virtue of the fact that many of the tubes to be expanded project from the associated tube sheet, while other tubes are flush with the face of such sheets. This situation in actual practice presents a rather significant limitation to an operator insofar as the conventional approach commonly employed is to utilize separate expanders on hand for each situation or apply different stop collars to the tube expander assemblies. It is evident, of course, that with this type of approach besides a burdensome and cumbersome task for the operator being developed there are significant drawbacks relating to the additional and unnecessary costs involved through use of different tube expander assemblies and/or collars therefor.
Heretofore known stop collar mechanisms for overcoming the above noted disadvantages associated with tube ends flush with or extending from the tube sheet or the like are characterized as being relatively more complicated in construction and more costly to produce and require tedious and precise adjustments for each different situation. By way of specific example, U.S. Pat. Nos. 1,680,922 and 2,649,889 generally describe thrust collars which are adjustable so as to accommodate for tube ends which may be either flush or project from the face of the tube sheet. In particular, the above patents each disclose a tube expander having an adjustable stop collar which is provided with an external threaded portion adapted to be threaded onto a sleeve member mounted on the thrust collar housing so that the axial position of the stop collar with respect to the end of the sleeve member can be adjusted as desired. This form of construction enables the tube expander to accommodate tubes having ends which are either flush with, or project from, the tube sheet. In the case of the former situation, the stop collar is positioned so that its end is flush with that of the sleeve member. As to the latter situation, the stop collar is positioned so that its end extends beyond the end of the sleeve member by a distance equal to the distance the tube is to project from the sheet.
Although the tube expanders described in the aforementioned patents can accommodate both flush and projecting tube ends, the position of the stop collar must be repeatedly readjusted since the depth of the recess defined by the interior of the stop collar and the end portion of the sleeve member must be set fairly accurately when the tool is used to expand tubes with projecting ends. This adjustment problem is rather time consuming. This problem is magnified when it is considered that during a typical installation for a boiler or heat exchanger there may be hundreds of tube ends which need to be expanded by the operator.
Moreover, the overall constructions of the noted category of stop collar apparatus is relatively expensive, especially given the need for cooperating threaded surfaces. Also, prior art arrangements do not permit the expander tool and stop collar to be readily converted for use with either flush or projecting tube ends in a manner which is as easy and rapid as could otherwise be desired.
In context of the prior art, I have invented an apparatus which overcomes the earlier noted shortcomings generally encountered in connection with known thrust collar devices used in association with tube expanding assemblies by providing a simple, versatile, economical, reliable, unique and unobvious apparatus including a thrust collar apparatus with a reversible collar for expanding tubes and the like which have their ends either projecting from the tube sheet or not.